The present invention relates to a transparent conductive element, an input device, and a display device. In particular, it relates to a transparent conductive element having an antireflection function.
In a display device such as electronic paper and an input device such as a touch panel, a transparent conductive element in which a transparent conductive layer is formed on a flat surface of a substrate is used. As the material for the transparent conductive layer used in this transparent conductive element, a high-refractive-index material (e.g., ITO (Indium Tin Oxide)) having a refractive index of about 2.0 is used. Accordingly, the reflectance is high depending on the thickness of the transparent conductive layer and the quality of the display device and the input device is sometimes degraded.
Conventionally, in order to improve the transmission characteristics of a transparent conductive element, a technique of forming an optical multilayer film is used. For example, in Japanese Unexamined Patent Application Publication No. 2003-136625, a transparent conductive element for a touch panel, in which an optical multilayer film is provided between a substrate and a transparent conductive film, is proposed. This optical multilayer film is formed by sequentially stacking a plurality of dielectric films having different refractive indices. However, according to this technique, the optical adjustment function becomes wavelength-dependent. Here, the optical adjustment function refers to the optical adjustment function for the transmission characteristics and/or reflection characteristics. Moreover, in recent years, because transparent conductive elements are used in various display devices and input devices, excellent electrical reliability is desired.